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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-07-05 00:14:42 +0300
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-08-29 19:20:48 +0300
commit444da518fd554eb1b9875dc97fac6ec249cee330 (patch)
tree66b30935a20522ea61e26fba47184b15c8173737 /kernel/rcu/rcutorture.c
parent31e7490741566d6f72be3a68bf9259a3bc2bc21d (diff)
downloadlinux-444da518fd554eb1b9875dc97fac6ec249cee330.tar.xz
rcutorture: Force occasional reader waits
Deferred quiescent states can interact with the scheduler, but rcu_torture_reader() does not force such interaction all that frequently. This commit therefore blocks for one jiffy after ten jiffies of read-side runtime. This has the beneficial effect of being most likely to block just after long-running readers, and it is exactly these readers that are most likely to have been preempted (in CONFIG_PREEMPT=y kernels). This in turn helps increase the probability that a deferred quiescent state will be seen by RCU's context-switch hooks. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/rcutorture.c')
-rw-r--r--kernel/rcu/rcutorture.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index c596c6f1e457..50a4f0ed4ebf 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1387,6 +1387,7 @@ static void rcu_torture_timer(struct timer_list *unused)
static int
rcu_torture_reader(void *arg)
{
+ unsigned long lastsleep = jiffies;
DEFINE_TORTURE_RANDOM(rand);
struct timer_list t;
@@ -1402,6 +1403,10 @@ rcu_torture_reader(void *arg)
}
if (!rcu_torture_one_read(&rand))
schedule_timeout_interruptible(HZ);
+ if (time_after(jiffies, lastsleep)) {
+ schedule_timeout_interruptible(1);
+ lastsleep = jiffies + 10;
+ }
stutter_wait("rcu_torture_reader");
} while (!torture_must_stop());
if (irqreader && cur_ops->irq_capable) {